JPH0715883B2 - Photovoltaic device manufacturing method and manufacturing apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for manufacturing a photovoltaic device manufactured by a plasma CVD method using a multi-chamber separation furnace, and more particularly to an optical device capable of significantly increasing the photoelectric conversion efficiency of the photovoltaic device. The present invention relates to a method and an apparatus for manufacturing an electromotive force element.

When a photovoltaic device is manufactured by the plasma CVD method using, for example, a three-chamber separation furnace, the substrates are sequentially accommodated in three metal gas chambers that are isolated and connected by a shutter, and the substrates are accommodated. An extremely high-purity thin-film forming gas (hereinafter, referred to as a generating gas) for generating a predetermined semiconductor thin film is supplied to the gas chamber, and is generated by a pair of electrodes (hereinafter referred to as a discharge electrode) facing each other. The use gas is decomposed to form a predetermined first layer thin film on the substrate surface. The metal gas chamber is grounded. After that, after the generation gas in the gas chamber is discharged, the substrate is moved to be accommodated in the adjacent gas chamber, and in this gas chamber as well, the generation gas having a different component from the above gas is fed. By glow discharge, a second thin film is formed on the surface of the first thin film of the substrate. Subsequently, after the generation gas in the gas chamber is discharged, the substrate is further moved to the adjacent gas chamber to be accommodated therein, and a predetermined generation gas having a different component from the gas is fed in the same manner as described above. By glow discharge, a third thin film is formed on the surface of the second thin film of the substrate. In other words, in the separation furnace, since the production gases with high-purity components that are different from each other are individually fed to the respective gas chambers, the interference of the production gases with different components is avoided, and the production gases are generated in each gas chamber. The quality of the formed thin film is not adversely affected by the decrease in the purity of the product gas.

However, when the production gas is glow-discharged in the gas chamber, a residue composed of the same components as the thin film produced on the substrate is attached and deposited on the inner wall surface of each metal gas chamber. Also, when the generated gas is decomposed by glow discharge, positive ions (hereinafter referred to as ions) are generated, and due to the electric field with the grounded metal gas chamber wall surface, the ions are generated on the gas chamber wall surface. The residue adhered to the inner wall surface of the gas chamber is collided at a high speed, and the residue is tapped off, so that some components of the residue are suspended in the gas chamber. In other words, even though the concentration of the production gas fed into the gas chamber is controlled to a constant value, some of the components of the residue knocked out by the ions are added to the production gas and the concentration is increased. As a result, the composition ratio of the generating gas for forming the thin film is disturbed and a good quality thin film cannot be formed,
It was found that this is a cause of hindering the increase in photoelectric conversion efficiency.

In view of the above-mentioned problems, the present invention is directed to suppressing the collision of ions generated by glow discharge with the inner wall surface of the gas chamber when generating a thin film of a photovoltaic element by a plasma CVD separation furnace. , A method for manufacturing a photovoltaic element and a device for manufacturing the photovoltaic element, which can increase the photoelectric conversion efficiency by maintaining a constant ratio of the components of the generating gas in the gas chamber and generating a high quality thin film. .

Hereinafter, a method of manufacturing a photovoltaic element and a manufacturing apparatus thereof according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing an apparatus for manufacturing a photovoltaic element, 1 is a preheating chamber in which a heating device is provided, 2 is a gas chamber for generating a P-type semiconductor layer, and 3 is I. A gas chamber for producing an N-type semiconductor layer, 4 a gas chamber for producing an N-type semiconductor layer,
Reference numeral 5 denotes a cooling chamber. Each of these chambers is made of, for example, stainless steel, which emits little gas, and is integrally assembled side by side. Further, the preheating chamber 1, the gas chambers 2, 3, 4 and the cooling chamber 5 are respectively provided at the same height position with the substrate carry-in ports 1a, 2a, 3a, 4a and 5a on the negative side and the cooling chamber 5. Has a substrate unloading port 5a 'on the other side. At the respective substrate loading ports 1a to 5a and the substrate loading port 5a ', there are provided shutters 1b to 5b and 5b' which can be airtightly closed and can be opened and closed. The chambers can be individually isolated. Reference numerals 2c, 3c and 4c are gas feed pipes which are provided in the upper part of the gas chambers and communicate with the insides of the gas chambers 2, 3 and 4, and the gas feed pipes 2c are gas for producing a P-type semiconductor (SiH ₄ + CH ₄ + B ₂ H ₆ +
H ₂ ) gas supply source 6, gas supply pipe 3c generates I-type semiconductor layer to generate gas (SiH ₄ ) gas supply source 7, and gas supply pipe 4c generates N-type semiconductor layer. Generation gas (SiH ₄
+ PH ₃ + H ₂ ) is connected to each of the gas supply sources 8, and a not-shown valve is controlled to send the generated gas to each of the gas chambers 2, 3, and 4. 1d to 5d are gas discharge pipes provided in the lower part of the gas chambers in communication with the preheating chamber 1, the gas chambers 2, 3, 4 and the cooling chamber 5, and each of the gas discharge pipes 1d to 5d has a valve (not shown). After that, it is connected to a vacuum pump (not shown) so that the preheating chamber 1, each of the gas chambers 2, 3, 4 and the cooling chamber 5 can be in a vacuum state. 9,9 ', 10,1
Reference numerals 0 ', 11, 11' denote discharge electrodes located above and below in the gas chambers 2, 3, 4 and facing each other and electrically insulated from the wall surface of the gas chamber. Electrodes 9,9 ', 10,1
0 ', 11, 11' are provided at positions that do not obstruct the openings of the substrate carry-in ports 2a, 3a, 4a.

In each of the preheating chamber 1, the gas chambers 2, 3, 4 and the cooling chamber 5, there is individually provided a substrate transport means (not shown), for example, a conveyor, which has a uniform height within a range of the substrate loading ports 1a to 5a. It is provided. Each of these substrate transfer means can transfer the substrate placed on the substrate transfer means to the adjacent gas chambers 2, 3, 4 and the cooling chamber 5 when the shutters 1b to 5b and 5b 'are opened. . Also, grounded metal gas chambers 2, 3,
In the inside of 4, the discharge electrodes 9, 9 ′, 10, 10 ′, 11, 11 ′ are opposed to each other by a gap between the electrodes and the inner wall surfaces of the gas chambers 2, 3, 4 An ion suppression electrode located along the inner wall surface
12, 12 ', 12 "are arranged so as to be electrically insulated from the inner wall surface, etc. The ion suppressing electrodes 12, 12', 12" are formed to have a high aperture ratio. It consists of a conductor 12a made of stainless steel, copper, aluminum or the like having a diameter of a predetermined dimension wound in a spiral cylindrical shape with a predetermined pitch, and its axial length dimension is the upper and lower discharge electrodes 9,
The ion suppressing electrodes 12, 12 ', 12 "are formed at a height position slightly longer than the facing distance of 9, 10, 10', 11, 11" and at the height position where the substrate transfer means is disposed. The pitch is increased so that the substrate conveyed by the substrate conveying means can pass through.

13a, 13b, 13c are discharge power sources consisting of direct current or high frequency power sources, each positive electrode is connected to the upper discharge electrodes 9, 10, 11 of each gas chamber 2, 3, 4 and the negative electrode is Side discharge electrode 9 ',
It is connected to 10 ', 11' and grounded, and the voltage between each discharge electrode can be individually adjusted by a voltage adjusting unit and a switch (not shown) provided in each discharge power supply 13a, 13b, 13c. It is possible to apply electricity to. 14a, 14b,
Reference numeral 14c denotes an ion suppressing power source, the negative electrodes of which are connected to the ion suppressing electrodes 12, 12 ', 12 ", and the positive electrodes of which are grounded.
The output voltage of 14a, 14b, and 14c can be adjusted in the range of 0 to -50 volts by a built-in voltage adjusting unit (not shown), and the ion suppressing electrodes 12, 12 are made by a switch (not shown). ′, 12 ″ can be individually charged, and these constitute a photovoltaic device manufacturing apparatus composed of a three-chamber separation furnace.

Next, a method of manufacturing a photovoltaic element by the photovoltaic element manufacturing apparatus including the three-chamber separation furnace configured as described above will be described. In the illustrated state, first, a vacuum pump (not shown) is driven to bring the gas chambers 2, 3, 4 and the cooling chamber 5 excluding the preheating chamber 1 into a vacuum state. After that, only the shutter 1b is opened, the substrate P is placed on the substrate transfer means (not shown) in the preheating chamber 1, the shutter 1b is closed, and the substrate P is heated by the heating device (not shown) provided in the preheating chamber 1. The preheating chamber 1 is evacuated. Subsequently, when the substrate P reaches a predetermined temperature, the shutter 2b is opened and the substrate transfer means in the preheating chamber 1 and the gas chamber 2 is driven to transfer the substrate P into the gas chamber 2 and the shutter 2b is closed. Then, the gas supply source 6 is placed in the gas chamber 2.
To supply a generating gas having a predetermined component ratio for generating a P-type semiconductor layer from the discharge electrode to the discharge electrodes 9 and 9 '.
High voltage is applied by 3 and power supply for ion suppression 1
A negative voltage of, for example, several volts is applied to the ion suppression electrode 12a by 4a. Therefore, due to the high voltage applied between the discharge electrodes 9 and 9 ', the gas for generation between the opposed discharge electrodes 9 and 9'is glow-discharged and decomposed, and the substrate P located between the discharge electrodes 9 and 9'is decomposed. A P-type semiconductor layer is formed on the surface of. At this time, the residue obtained by decomposing the gas also adheres to the inner wall surface of the gas chamber 2. On the other hand, the ions N generated by the glow discharge are grounded and rush toward the metal gas chamber wall surface of zero voltage,
Under the influence of the electric field of the ion suppression electrode 12 which is arranged in front of the inner wall surface and is applied with a negative voltage, the ions N are attracted to the ion suppression electrode 12 and flow to the ground, and the ions N are formed on the inner wall surface of the gas chamber 2. Does not reach. That is, since the generated ions N do not collide with the residue attached to the inner wall surface of the gas chamber 2 and knock out the residue, the gas component ratio in the gas chamber 2 is sent from the gas supply source 6. The generated P-type semiconductor layer can be kept at a predetermined component ratio, and the generated P-type semiconductor layer has extremely good characteristics. Then, after the semiconductor layer is generated on the substrate P, the application of the voltage to the discharge electrodes 9, 9'is stopped, and the generation gas in the gas chamber 2 is discharged to make a vacuum state. After that, the shutter 3b is opened, the substrate transfer means (not shown) in the gas chambers 2 and 3 is driven to transfer the substrate P into the gas chamber 3, and the shutter 3b is closed. Subsequently, the gas supply source 7 supplies a generation gas having a predetermined component ratio to the gas chamber 3 to generate the I-type semiconductor layer, and a high voltage is applied to the discharge electrodes 10 and 10 'to generate the same as the above. The discharge gas is glow-discharged to form an I-type semiconductor layer on the surface of the P-type semiconductor layer of the substrate P. Also in this case, the ions N generated by the gas decomposition by the glow discharge are attracted to the ion suppressing electrode 12 ', and do not reach the inner wall surface of the gas chamber 3 and strike out the residue attached to the inner wall surface. There is no. Therefore, in the gas chamber 3, a part of the components generated from the residue is not mixed in the fed production gas, and an I-type semiconductor layer having excellent characteristics is produced. After that, in the same manner as above, the gas chamber 3
After the inside is evacuated, the shutter 4b is opened, the substrate P in the gas chamber 3 is transferred into the gas chamber 4, and the shutter 4b is closed to generate a generation gas for generating an N-type semiconductor layer from the gas supply source 8. It is fed into the chamber 4 to form an N-type semiconductor layer on the surface of the I-type semiconductor layer of the substrate P. Also in this case, the generated ions N
Does not reach the inner wall surface of the gas chamber 4 and the composition ratio of the gas does not change, so that an N-type semiconductor layer having excellent characteristics is produced. After the N-type semiconductor layer is generated in this way, the inside of the gas chamber 4 is evacuated to open the shutter 5b, and the substrate transfer means in the gas chamber 4 and the cooling chamber 5 is driven so that the inside of the gas chamber 4 is driven. Substrate P is transferred to the cooling chamber 5, the substrate P is brought to a predetermined temperature in the cooling chamber 5, the shutter 5b 'is opened, and the substrate transfer means in the cooling chamber 5 is driven to transfer the substrate P to the substrate unloading port.
It is carried out from the cooling chamber 5 through 5a '.

Thus, the P-type, I-type, and N-type semiconductor layers are sequentially stacked on the surface of the substrate P, and the photovoltaic element is completed. Since each of the semiconductor layers P, I, and N is generated by the generating gas having a constant component ratio in the isolated gas chamber, each semiconductor layer has extremely high purity and stable components. Thus, the completed photovoltaic device has extremely high photoelectric conversion efficiency.

In the present embodiment, one substrate P is intermittently transported from the preheating chamber 1 to the cooling chamber 5 and each gas chamber is supplied with a production gas having a different component. Although the process of manufacturing the element has been described, the number of substrates P to be conveyed is appropriate. Further, the components of the generated gas are also appropriate and are not limited to them. Further, although the ion-suppressing electrode is formed of a spirally-cylindrical conductor, it is also possible to use a curved and bent conductor made of a conductor. Further, the wire net may be formed in a cylindrical shape. in this case,
The same can be used by forming a substrate insertion opening having a predetermined shape at a position facing the substrate transfer position. Furthermore, in the present embodiment, for the sake of explanation, a manufacturing process has been shown in which one substrate is intermittently transported from the preheating chamber to the cooling chamber to the cooling chamber to sequentially stack thin films. Needless to say, the same effect can be obtained even when a new substrate is housed in the preheating chamber and the photovoltaic elements are continuously manufactured with the substrate housed in each chamber. Note that the shutter that separates each gas chamber may be partitioned instead of the gas curtain.

As described above in detail, according to the method for manufacturing a photovoltaic element of the present invention, the ions generated in each gas chamber are suppressed from colliding with the inner wall surface of each gas chamber by the action of the ion suppression electrode. Therefore, the residue of the decomposition gas attached to the inner wall surface is not knocked out. Therefore, without changing the composition ratio of the production gas sent to the gas chamber, it is possible to stably produce a semiconductor layer of good quality and excellent characteristics by the production gas having a constant composition ratio on the substrate. Therefore, a photovoltaic element having high photoelectric conversion efficiency can be stably manufactured. In addition, the photovoltaic device manufacturing apparatus according to the present invention,
By providing an ion suppression electrode on the side of the facing gap of the discharge electrodes arranged opposite to each other, that is, in front of the wall surface of the gas chamber in the gas chamber where the semiconductor layer is generated, and by setting this to a negative voltage or zero voltage, the gas chamber The ions generated in 1 can be attracted, and it is possible to easily prevent the ions from colliding with the inner wall surface of the gas chamber. Further, since the ion suppression electrode is provided in front of the inner wall surface of the gas chamber, it does not obstruct the space where the discharge electrode faces and does not adversely affect the semiconductor layer formed on the substrate. Further, the ion suppressing electrode is simple in structure and mounting, and is inexpensive and can achieve the purpose.

[Brief description of drawings]

FIG. 1 is a schematic structural sectional view showing an apparatus for manufacturing a photovoltaic element according to the present invention. 1 ... Preheating chamber, 2, 3, 4 ... Gas chamber, 5 ... Cooling chamber, 9, 9 ', 10, 1
0 ', 11, 11' ... Discharge electrode, 12, 12 ', 12 "... Ion suppression electrode, 13a, 13b, 13c ... Discharge power supply, 14a, 14b, 14c ... Ion suppression power supply, P ... Substrate, N ... ion.

Claims (2)

[Claims] 1. A pair of electrodes facing each other is arranged in each of the gas chambers of a separation furnace composed of a plurality of metal gas chambers that are partitioned and connected to each other, and a production gas for producing a semiconductor thin film is sent. In the method of manufacturing a photovoltaic element, in which a supply gas is generated, the discharge gas is glow-discharged, a substrate is sequentially housed in the gas chamber, and a semiconductor thin film is generated on the surface of the substrate. The ion suppression electrode having a high aperture ratio located between the electrode and the inner wall surface of the gas chamber is arranged along the inner wall surface, and the ion suppression electrode is set to a negative voltage with respect to the gas chamber, A method of manufacturing a photovoltaic element, which suppresses collision of ions generated by glow discharge of a generating gas in the gas chamber with an inner wall surface of the gas chamber to generate a semiconductor thin film. 2. A production gas for producing a semiconductor thin film, comprising a separation furnace comprising a plurality of metallic gas chambers which are partitioned and connected to each other, and a pair of electrodes facing each other are arranged in each of the gas chambers. In the apparatus for manufacturing a photovoltaic element for glow-discharging the gas for generation, which is lateral to the gap between the electrodes and located between the electrode and the inner wall surface of the gas chamber, An apparatus for manufacturing a photovoltaic element, comprising: an ion suppression electrode having a high aperture ratio, which is disposed along an inner wall surface; and an ion suppression power supply that sets the ion suppression electrode to a negative voltage with respect to the gas chamber.